Videos do not work in Lightroom 4.1 and 4.2 RC

I have video files in several formats (including recent ones like the iPhone 4s and the Nikon D5100). In Lightroom 3 they work to the extent advertised in Lightroom 3; an image of the video is shown and I can double-click on the video and it will be launched and played in the external media application (usually QuickTime).

In Lightroom 4.1 and 4.2 RC, I can't do anything with the video. All that happens is that it 'loads' forever. ie. The loading... widget with the swirly stays forever and the swirly never stops swirling. All of the Edit In... options are greyed out, so video support for me in Lightroom 4 is less functional than in Lightroom 3. I can't even do what I used to do and launch them in an external application. Needless to say, none of the new video features touted in Lightroom 4 work either.

I've attached the system information from Lightroom. Hopefully you guys can sort this out. I'd like to upgrade to Lightroom 4 but can't if none of my videos will play.

LR 4.2 RC: I would like to make a suggestion on playback of HD video files. Playback starts out fine then goes downhill with stuttering and jerky playback. I am convinced the main problem here is sync between video and audio. Yet these files playback perfectly on my Win 7 PC using WMP, and other external players. Rather than reinventing the wheel for video timing (think reclock), wouldn't it be easier to provide an option for users to choose an external player? Another alternative here is embedding specific codecs within LR. However I'm guessing developing such codes for HD video is no easy task. Just ask the folks who developed codecs for home theater PCs bitstreaming HD video. I've seen the same issues in the early phases of HTPC as I'm seeing here. Perhaps borrowing on codecs such as LAV filters would be far easier here. As of now, relying on the users default system codecs is just begging for endless consistency problems.
Additionally with improper codecs, I find LR has the tendency to really bog down, or freeze up. I am also suspicious importing my AVCHD files are creating slow performance in develop module, even when I am working on jpegs. Folders without these AVCHD files seem to be more responsive to changes in develop.